Author: SM. KhalilPublisher:
ISBN:
Category : Admixtures
Languages : en
Pages : 11
Book Description
Superplasticizing chemical admixtures enable the production of either flowing concrete or concrete with normal workability with very low water/cement (W/C) ratios. The production of low W/C ratio concrete with high strength is of considerable interest to the precast concrete industry. However, it has often proved very difficult, when using superplasticizing chemical admixtures, to entrain an adequate air void system in these low W/C ratio concretes, giving rise to uncertainty regarding the freeze-thaw durability of such concretes. Using ASTM Test for Critical Dilation of Concrete Specimens Subjected to Freezing (C 671 - 77) and Test for Resistance of Concrete to Rapid Freezing and Thawing (C 666 - 77), it is shown that the durability of low W/C ratio, nonair-entrained concrete containing superplasticizers is markedly affected by the aggregate source. Tests conducted on concrete batched at a number of precast concrete plants in Western Canada show that adequate durability may be achieved with some of the principal aggregate sources currently used in precast concrete production.